Dominic Thiem has become 'spectacularly consistent' this year and is now ready to compete at the same level as the Big Three, says his coach.
Thiem won his first Grand Slam title in 2020 and has beaten both Rafael Nadal (twice) and Novak Djokovic this season.
He also won all three of his matches against Roger Federer in 2019, and Massu believes the Austrian deserves to be considered in the same class.
"The level of consistency Dominic Thiem has had in the last two years is spectacular," Massu said.
"He has the talent to do things much better than you think. It will always be difficult to play against the best in history (the Big three), but if there is anyone who can compete equally with them it is Dominic."
According to Massu, the biggest change in Thiem has not been raising his level, but being able to produce it more often.
"After 2019, it was already difficult to overcome what he had done: he won five tournaments in the year, reached a Grand Slam final.
"It was super complex to do a better year and with few tournaments he did it: he finished number three, winning his first Grand Slam and winning on surfaces where previously the results were not the same as on clay.
“He works 100% every day, he has a spectacular mentality, apart from the talent and the power, how sacrificed he is.
"He has a lot to keep improving. It is not easy to do so because the margin is very small at this level."
“If you do what you have to do, you will always have a chance of winning.
"He is very complete; he plays well on all surfaces, he has a great serve, forehand, backhand, he moves well."
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